This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
BS base station
DL downlink (eNB towards UE)
eNB E-UTRAN Node B (evolved Node B)
EPC evolved packet core
E-UTRAN evolved UTRAN (LTE)
FDMA frequency division multiple access
IMTA international mobile telecommunications association
ITU-R international telecommunication union-radiocommunication sector
LTE long term evolution of UTRAN (E-UTRAN)
LTE-A LTE advanced
MAC medium access control (layer 2, L2)
MM/MME mobility management/mobility management entity
NAS non-access stratum
NodeB base station
OFDMA orthogonal frequency division multiple access
O&M operations and maintenance
PDCP packet data convergence protocol
PHY physical (layer 1, L1)
Rel release
RLC radio link control
RRC radio resource control
RRM radio resource management
SGW serving gateway
SC-FDMA single carrier, frequency division multiple access
UE user equipment, such as a mobile station, mobile node or mobile terminal
UL uplink (HE towards eNB)
UTRAN universal terrestrial radio access network
One modern communication system is known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA). In this system the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.11.0 (2009-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LIE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.3.0 (2010-03).
FIG. 1 reproduces FIG. 4.1 of 3GPP TS 36.300 V8.11.0, and shows the overall architecture of the EUTRAN system (Rel-8). The E-UTRAN system includes eNBs, providing the E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UEs. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to a S-GW by means of a S1 interface (MME/S-GW 4). The S1 interface supports a many-to-many relationship between MMEs/S-GWs/UPEs and eNBs.
The eNB hosts the following functions:
functions for RRM: RRC, Radio Admission Control, Connection Mobility Control,
Dynamic allocation of resources to UEs in both UL and DL (scheduling);
IP header compression and encryption of the user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards the EPC (MME/S-GW);
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
a measurement and measurement reporting configuration for mobility and scheduling.
Also of interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10) targeted towards future IMTA systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference in this regard may be made to 3GPP TR 36.913, V9.0.0 (2009-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 9). Reference can also be made to 3GPP TR 36.912 V9.2.0 (2010-03) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Feasibility study for Further Advancements for E-UTRA (LTE-Advanced) (Release 9). A goal of LIE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is directed toward extending and optimizing the 3GPP LIE Rel-8 radio access technologies to provide higher data rates at lower cost. LTE-A will be a more optimized radio system fulfilling the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Rel-8.
Of particular interest herein is 3GPP TS 36.331 V9.3.0 (2010-06) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification (Release 9), in particular section 5.3.3, RRC connection establishment and section 5.3.8, RRC connection release. FIG. 3 herein reproduces FIG. 5.3.3.1-1: RRC connection establishment, successful; FIG. 4 herein reproduces FIG. 5.3.3.1-2: RRC connection establishment, network reject; and FIG. 5 herein reproduces FIG. 5.3.8.1-1: RRC connection release, successful, from 3GPP TS 36.331.
In the LTE system the RRC Connection Setup procedure includes the three messages shown in FIG. 3, i.e., RRCConnectionRequest, RRCConnectionSetup and RRCConnectionSetupComplete. In a case where the eNB can accept the RRC Connection Request sent from the UE when in the RRC Idle mode it responds with the RRC Connection Setup, and the UE becomes RRC Connected. On the other hand, if the eNB cannot accept the RRC Connection Request for some reason (e.g., congestion) the eNB replies with the RRCConnectionReject message shown in FIG. 4.
In RRC Connection Reject message the eNB can indicate to UE that it should wait a certain time before it re-tries another attempt to set up the RRC Connection. As is stated in section 5.3.3.8, the UE starts a timer T302 with the timer value set to the waitTime specified by the RRCConnectionReject message.
RRCConnectionReject-r8-IEs ::=SEQUENCE {waitTimeINTEGER (1..16),nonCriticalExtensionRRCConnectionReject-v8a0-IEsOPTIONAL}